Don't have a Triumph... have an T/C Omega. I also had no luck with the Barnes 250 MZ & 285 MZ with BH209. If you want to stay with Barnes offerings... I had good groups with the following in my Omega and my buddy's Encore with 90 - 100grs of BH209:
1. 245 Barnes Spit-Fire MZ with supplied yellow sabot or Harvester yellow sabot for boat tails.
2. 250 Barnes TMZ (the flat based bullet.. not the boat tail) and discard the EZ-load sabot it comes with... and use your HPH-12 instead.
Keep shooting...I think you just haven't found the right combo yet....
Good luck... Rob